1. Field of the Invention
This invention relates generally to surgical devices and, more particularly, to surgical devices used in long bones.
2. Related Art
Current modular implant instrument systems are such that there are two separate reamers provided in preparing the femoral canal. One reamer is used to prepare the distal portion of the canal. The reamer is then removed from the drill and the second reamer is attached to the drill to prepare the proximal portion of the canal. Such systems are labor intensive and time consuming.
Other systems build on or add to the distal reamers. In these systems, the surgeon would have to build the reamer before attaching to the drill. The surgeon is typically required to ream with the distal reamer until the desired distal diameter is achieved. At this point the surgeon has to remove the distal reamer from the drill and add the proximal reamer/s from the end of the distal reamer shaft. In this system, both the proximal reamer and distal reamer have their own depth marks to reference the greater trochanter. Neither reamer has a common reference mark between the reamers. Therefore, the reamers may still be inexact in preparing the distal to proximal portions of the femoral canal because of errors such as tolerance stack and human error. With the addition of sleeves, another tolerance (sleeve length) must be taken into account when reaming the proximal depth.
Yet another example uses a combination proximal and distal reamer (or plurality of reamers) having a flexible core within the reamer to allow the proximal portion to flex and prepare the medial side of the metaphyseal within the femur. It can also be utilized to fit more within the bow of the femur. This flexible core can create a series of potential issues. First issue is the ability to clean the tool core. With spiral cuts within the core or other means to create flexibility, the potential exists for blood, tissue, or small bone fragments to be caught within the core of the reamer. Another issue is with the potential of the system binding such that the flexible core creates a “coiling” effect and doesn't allow the reamers to turn and cut due to more torsional resistance of the bone cutting than torsional resistance of the flexible core.
For a proximal reamer design, the shaft drives both the proximal and distal reamers simultaneously. The elongated shaft guides the proximal broach to remove the medial side of the metaphyseal. Therefore, the purpose of having the modular proximal reamer is to have exposure for the elongated shaft to use as a guide in broaching.
In other embodiments, the distal reamer is utilized for reaming out the distal segment only. The surgeon disconnects the distal reamer and connects to a proximal reamer. The proximal reamer requires a distal pilot to be attached, for guiding purposes during the preparation of the metaphyseal for the implant.
Other reamers have a trial head/neck that can be attached to a reamer or broach for a trial reduction. The head/neck trial assembly is attached by a handle to create the version desired. The head/neck assembly can also be adjusted proximally or distally to select the desired height as well. The location of the head/neck assembly relative to the reamer or broach may be difficult to replicate with the implant. There are no references to locate the head/neck assembly in locating height, thus the implant does not necessarily reflect what the surgeon measured during the trial reduction. The surgeon has to somewhat guess and estimate where the implant will be located and place the head/neck assembly to that location accordingly.
Other systems with a distal reamer, proximal reamer, and trial neck utilize guide channels on the trial neck adaptor to establish anti-rotation and implant orientation. The proximal reamer is required to have straight flutes in order to have guide channels. The guide channels dictate the cutting geometry that can be utilized for the proximal reamer. This system also does not facilitate the ability for the proximal and distal reamers to be modular such that a surgeon can have various proximal reamers for a given distal reamer.
There remains a need in the art for increasing accuracy while decreasing the number of steps/instruments that is required of systems that utilize proximal/distal reaming systems. In addition, accuracy and decreasing the number of steps may also be achieved with respect to the method of performing a trial reduction for modular implant designs.
In addition, orienting the trial neck in situ without having to remove the reamer construct, especially in small incisions, may be beneficial.